Ultrasound diagnostic apparatus and ultrasound image producing method

ABSTRACT

In an ultrasound diagnostic apparatus of the present invention, the controller writes and reads element data of one frame into and out from two or more buffer memories  21   a   , 21   b, . . .    21   i  sequentially frame by frame and assigns the element data of one frame sequentially read out from the buffer memories to a plurality of arithmetic blocks of a signal processor, wherein the element data assigned is subjected to processing by each of a plurality of arithmetic cores in the plurality of arithmetic blocks to produce an image signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Division of copending U.S. application Ser. No.14/264,603, filed Apr. 29, 2014, (now U.S. Pat. No. 10,321,895 issuedJun. 18, 2019), which is a continuation application of InternationalApplication PCT/JP2012/077348 filed on Oct. 23, 2012, which claimspriority under 35 U.S.C. 119(a) to Application No. 2011-246309 filed inJapan on Nov. 10, 2011 and Application No. 2012-181612 filed in Japan onAug. 20, 2012, all of which are hereby expressly incorporated byreference in their entirety into the present application.

BACKGROUND OF THE INVENTION

The present invention relates to an ultrasound diagnostic apparatus andan ultrasound image producing method and particularly to an ultrasounddiagnostic apparatus having a battery to supply power to each componentof an ultrasound probe and a diagnostic apparatus body.

Conventionally, ultrasound diagnostic apparatuses using ultrasoundimages have been employed in the medical field. In general, this type ofultrasound diagnostic apparatus comprises an ultrasound probe having abuilt-in transducer array and an apparatus body connected to theultrasound probe. The ultrasound probe transmits an ultrasonic beamtoward the inside of a subject's body, receives ultrasonic echoes fromthe subject, and the apparatus body electrically processes the receptionsignals to produce an ultrasound image.

In such ultrasound diagnosis, various examinations such as B-modeexamination, M-mode examination, CF-mode examination and PW-modeexamination are performed. In recent years, an ultrasound diagnosticapparatus capable of those examinations has been reduced in size byadopting an application specific integrated circuit (ASIC) or aprocessor and is applied as a mobile ultrasound diagnostic apparatus,for example. However, when those various examinations are carried out bya single apparatus, since signal processing, image processing or otherprocessing requires many arithmetic operations, there is a problem thatprocessing speed of the apparatus decreases.

As a technology for improving the processing speed, ultrasounddiagnostic apparatuses which perform parallel arithmetic operationsusing a large number of arithmetic cores in signal processing and thelike have been proposed, as disclosed in JP 2006-174902 A.

The apparatus disclosed in JP 2006-174902 A divides a measurement regioninto plural regions in a scanning line direction, and assigns anarithmetic core to each of the divided regions, whereby image processingis carried out in a parallel fashion in the scanning line direction, andthus the processing speed can be improved.

However, there is a demand for further improvement of processing speedin the recent ultrasound diagnosis which is becoming more and morecomplicated, like in the case where two or more examinations such asB-mode examination, CF-mode examination and PW-mode examination aresimultaneously executed.

SUMMARY OF THE INVENTION

The present invention has been made to solve the above-described problemof the prior art and has an object to provide an ultrasound diagnosticapparatus and an ultrasound image producing method that can improve theprocessing speed in producing an ultrasound image.

The ultrasound diagnostic apparatus according to the present inventioncomprises: a transducer array; a transmission circuit configured totransmit an energy beam toward a subject; a reception circuit configuredto process a reception signal outputted from the transducer array thatreceived ultrasonic waves generated from the subject upon transmissionof the energy beam to thereby generate element data; two or more buffermemories into each of which element data of one frame is written; asignal processor constituted with a plurality of arithmetic blocks eachincluding a plurality of arithmetic cores and configured to produce animage signal through processing of the element data of one frame readout from each of the buffer memories by the plurality of arithmeticcores in the plurality of arithmetic blocks; and a controller configuredto write and read element data into and out from the two or more buffermemories sequentially frame by frame and to assign the element data ofone frame read out to the signal processor to the plurality ofarithmetic blocks sequentially, to thereby cause the plurality ofarithmetic cores to perform processing on the element data.

In B-mode processing, the controller can assign the element data of oneframe to the plurality of arithmetic blocks for every plurality ofscanning lines, defines a plurality of divisional regions formed bydividing a measurement region in a depth direction for each of thearithmetic blocks, and assigns the divisional regions to the arithmeticcores one by one.

The controller can assign CF-mode processing and B-mode processing tothe plurality of arithmetic blocks. The controller can assign CF-modeprocessing, PW-mode processing and B-mode processing to the plurality ofarithmetic blocks. In addition, the controller can assign CF-modeprocessing, PW-mode processing, B-mode processing and M-mode processingto the plurality of arithmetic blocks.

In B-mode processing, the controller can control the transmissioncircuit and the reception circuit to transmit and receive ultrasonicwaves in different directions from one another and performs spatialcompounding in each of the plurality of arithmetic blocks.

Preferably, each of the plurality of arithmetic blocks includes a superfunction unit, and the controller causes the super function unitincluded in each of the arithmetic blocks to perform frequency analysisin CF-mode processing.

Preferably, the energy beam is one of an ultrasonic beam and anirradiation light beam.

The ultrasound image producing method according to the present inventioncomprises the steps of: emitting an energy beam toward a subject;receiving by a transducer array ultrasonic waves generated from thesubject upon transmission of the energy beam; generating element data byprocessing in a reception circuit a reception signal outputted from thetransducer array that has received the ultrasonic waves; writing elementdata of one frame into each of two or more buffer memories in such amanner that the two or more buffer memories correspond to frames one byone; producing an image signal by assigning the element data of oneframe sequentially read out from the buffer memories to a plurality ofarithmetic blocks, and causing each of a plurality of arithmetic coresincluded in the plurality of arithmetic blocks to perform processing onthe element data of one frame assigned; and repeating writing andreading element data into and out from the two or more buffer memoriesframe by frame.

According to the present invention, element data is alternately writteninto and read out from two buffer memories for every frame, and theread-out element data of one frame is assigned to a plurality ofarithmetic blocks to be processed, whereby the processing speed inproducing an ultrasound image can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of an ultrasounddiagnostic apparatus according to Embodiment 1 of the invention.

FIG. 2 is a block diagram illustrating configurations of a data IF unit,a BLIF unit and an element memory.

FIG. 3 is a flow chart illustrating an operation in Embodiment 1.

FIG. 4 is a schematic view illustrating a measurement region in a B-modeexamination.

FIG. 5 is a schematic view of B-mode element data stored in an elementmemory.

FIG. 6 is a schematic view illustrating a measurement region in theB-mode examination and a region of interest in a CF-mode examination.

FIG. 7 is a schematic view of element data in B-mode and element data inCF-mode stored in the element memory.

FIG. 8 is a schematic view of signal processing on element data inCF-mode.

FIG. 9 is a view illustrating how a B-mode image, a CF-mode image and aPW-mode image are simultaneously displayed.

FIG. 10 is a timing chart showing writings and readings of element datainto and out from two buffer memories.

FIG. 11 is a view illustrating assignment of a plurality of blocks to aplurality of scanning lines in spatial compounding.

FIG. 12 is a block diagram illustrating a configuration of an ultrasounddiagnostic apparatus according to Embodiment 2.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described below based onthe appended drawings.

Embodiment 1

FIG. 1 illustrates a configuration of an ultrasound diagnostic apparatusaccording to Embodiment 1 of the invention. The ultrasound diagnosticapparatus includes a probe 1, which is connected to a transmissioncircuit 3 and a reception circuit 4 via a multiplexer 2. The receptioncircuit 4 is connected to an A/D converter 5, a data interface (IF) unit6, a block interface (BLIF) unit 7, a digital scan converter (DSC) 8 anda monitor 9 in order, and the data IF unit 6 is connected to an elementmemory 10, while the BLIF unit 7 is connected to a signal processor 11and a cine-memory 12.

The transmission circuit 3, the reception circuit 4, the A/D converter 5and the BLIF unit 7 are connected to a CPU 13. The CPU 13 is alsoconnected to an operating unit 14 and a power source/battery unit 15.

The probe 1 includes a transducer array in which a plurality oftransducer elements are arranged one-dimensionally or two-dimensionally.These transducer elements each transmit ultrasonic waves according totransmission pulses supplied from the transmission circuit 3 via themultiplexer 2 and receive ultrasonic echoes from the subject to outputreception signals. Each of the transducer elements comprises a vibratorcomposed of a piezoelectric body and electrodes each provided on bothends of the piezoelectric body. The piezoelectric body is composed of,for example, a piezoelectric ceramic represented by a lead zirconatetitanate (PZT), a piezoelectric polymer represented by polyvinylidenefluoride (PVDF), or a piezoelectric monochristal represented by leadmagnesium niobate lead titanate solid solution (PMN-PT).

When the electrodes of each of the vibrators are supplied with a pulsedvoltage or a continuous-wave voltage, the piezoelectric body expands andcontracts to cause the vibrator to produce pulsed or continuousultrasonic waves. These ultrasonic waves are combined to form anultrasonic beam (energy beam). Upon reception of propagating ultrasonicwaves, each vibrator expands and contracts to produce an electricsignal, which is then outputted as a reception signal of the ultrasonicwaves.

The multiplexer 2 selects transducer elements to be used in a singletransmission, connects the selected transducer elements to thetransmission circuit 3 at the timing of transmission, and connects thetransducer elements to the reception circuit 4 at the timing ofreception.

The transmission circuit 3 includes, for example, a plurality ofpulsers, adjusts the delay amounts for the respective transmissionpulses based on a transmission delay pattern selected according to aninstruction signal transmitted from the CPU 13 such that the ultrasonicwaves transmitted from a plurality of transducers of the probe 1 form anultrasonic beam, and supplies the transducers with delay-adjustedtransmission pulses.

In accordance with the instruction signal from the CPU 13, the receptioncircuit 4 amplifies reception signals transmitted from the respectiveelements of the transducer array.

In accordance with the instruction signal from the CPU 13, the A/Dconverter 5 performs A/D conversion on the reception signals amplifiedin the reception circuit 4 to generate element data. Under the controlof the CPU 13, the data IF unit 6 communicates between the A/D converter5 and the element memory 10 or between the element memory 10 and theBLIF unit 7. The element memory 10 stores element data generated by theA/D converter 5 sequentially via the data IF unit 6. Under the controlof the CPU 13, the BLIF unit 7 communicates between the signal processor11 and the data IF unit 6, the cine-memory 12 or the DSC 8.

The signal processor 11 comprises a plurality of blocks 16 (BL0 to BLm)connected in parallel to the BLIF unit 7. Each of the blocks includes ablock controller (BLC) 17 connected to the BLIF unit 7, and the BLC 17is connected to a plurality of arithmetic cores (CO0 to COn) 18 and asuper function unit (SFU) 19. The signal processor 11 produces ascanning line signal (sound ray signal) in which focuses of theultrasonic echo are concentrated, and in particular a plurality ofscanning lines are each produced by the assigned blocks. The pluralityof arithmetic cores 18 each perform phasing addition on the element dataunder the control of the BLC 17. The SFU 19 performs arithmeticoperations such as fast Fourier transform (FFT) and trigonometricoperations. The BLC 17 controls the arithmetic operations by theplurality of arithmetic cores 18 and the SFU 19 to thereby controlproduction of scanning line signals in each of the blocks.

The DSC 8 converts the scanning line signals produced in the signalprocessor 11 into image signals compatible with an ordinary televisionsignal scanning mode (raster conversion).

The monitor 9 includes a display device such as an LCD, for example, anddisplays an ultrasound diagnostic image based on the image signalsproduced by the DSC 8.

The CPU 13 controls the components in the ultrasound diagnosticapparatus according to the instruction entered by an operator using theoperating unit 14.

The operating unit 14 is provided for the operator to perform inputoperations and may be composed of, for example, a keyboard, a mouse, atrack ball, and/or a touch panel.

The power source/battery unit 15 supplies the components in theultrasound diagnostic apparatus with power.

The controller in the present invention comprises the CPU 13 and theBLCs 17 in the respective blocks.

Next, the configurations of the data IF unit 16, the BLIF unit 7 and theelement memory 10 are described in detail.

As illustrated in FIG. 2, the element memory 10 includes two buffermemories 21 a and 21 b into each of which element data of one frame iswritten. The data IF unit 6 connected to the element memory 10 includesa changeover switch 22 a connected to the buffer memory 21 a and achangeover switch 22 b connected to the buffer memory 21 b. Thechangeover switches 22 a and 22 b are connected to the A/D converter 5and to a BUS selector 23 provided in the BLIF unit 7. The BUS selector23 is connected to the respective blocks 16 in the signal processor 11,the cine-memory 12 and the DSC 8. In addition, the BLIF unit 7 includesa BUS controller 24, and the BUS controller 24 is connected to the BUSselector 23, the changeover switches 22 a and 22 b, and the CPU 13.

The changeover switches 22 a and 22 b each comprise a couple of inputterminals a and b along with a single output terminal c, constituting atwo-to-one changeover switch. In each of the changeover switches 22 aand 22 b, the input terminal a is connected to the A/D converter 5 whilethe other input terminal b is connected to the BUS selector 23, and theoutput terminal c is connected to its corresponding buffer memory 21 aor 21 b in the element memory 10. By having such configuration, when theinput terminal a is connected to the output terminal c, element datafrom the A/D converter 5 can be written into the buffer memory 21 a or21 b, and when the input terminal b is connected to the output terminalc on the other hand, element data can be read out from the buffer memory21 a or 21 b to the signal processor 11.

The changeover switches 22 a and 22 b are switched over frame by framebased on the instruction signal from the BUS controller 24. For example,the BUS controller 24 outputs an instruction signal for each frame, andthe instruction signal is inputted in the changeover switch 22 a, whilean inverted instruction signal is inputted in the changeover switch 22b. In this manner, in each of the changeover switches 22 a and 22 b,connection of the output terminal c to the input terminal a or b isinverted between the changeover switches 22 a and 22 b, and suchchangeover of the connection is made frame by frame. Accordingly,element data can be written into and read out from the buffer memories21 a and 21 b alternately frame by frame.

Element data read out from the element memory 10 is outputted to therespective blocks in the signal processor 11 through the BUS selector23.

Next, the operation of Embodiment 1 will be described referring to theflowchart of FIG. 3.

First, once examination information including the patient informationand an examination request is entered from the operating unit 14 in theexamination information input mode in Step S1, the CPU 13 waits for aninstruction from an operator to start the examination in Step S2. Oncethe instruction to start the examination is entered through theoperating unit 14, the CPU 13 proceeds to Step S3 where the examinationmode is executed, and thereafter waits for an instruction from theoperator to terminate the examination in Step S4. When the instructionto terminate the examination is entered, a series of examinationprocessing is terminated, leaving the process as it then stands, whereaswhen an instruction not to terminate but to continue the examination isentered, the operation returns to step S1 to receive examinationinformation again.

In the examination mode in Step S3, one or more of previously setexamination modes such as brightness mode (B-mode), color flow mode(CF-mode), pulsed wave mode (PW-mode), and motion mode (M-mode) may beselected to execute the ultrasound diagnosis. That is, the CPU 13 checksexamination information entered in Step S1 to determine which mode hasbeen designated and, upon verifying designation of B-mode in Step S11,the operation proceeds to Step S12 to execute examination in B-mode.

Specifically, as illustrated in FIG. 4, the transducer array in theprobe 1 sequentially transmits a B-mode ultrasonic beam toward thesubject, for example, using 16 elements for one transmission, receivesan ultrasonic echo from a predetermined measurement region F and outputsa reception signal, which is subjected to A/D conversion to obtain theelement data in B-mode. At this time, focus points P0 to P49 are placedin the measurement region F at the depths respectively at which themeasurement region F is divided into, for example, 50 regions in thedepth direction, and the B-mode ultrasonic beam is sequentiallytransmitted from and received by the respective elements so as to formthe scanning lines L0 to Ln each of which includes the focus points P0to P49. As illustrated in FIG. 5, the B-mode element data e0 to e15obtained so as to correspond to the focus points PO to P49 in themeasurement region F is sequentially stored in the element memory 10 foreach frame.

The B-mode element data stored in the element memory 10 is divided inthe scanning direction, separately inputted in each of the blocks in thesignal processor 11 and processed therein. In an example where thesignal processor 11 has 5 blocks (BL1 to BL5), and each of the blockshas 50 arithmetic cores CO0 to CO49 constituting the arithmetic cores18, the BLC 17 in each of the blocks divides the measurement region Finto 5 regions (regions B) in the scanning direction and also into 50regions in the depth direction so as to form 250 divisional regions R,thereafter inputs the B-mode element data contained in the 5 regions B(B-mode element data of n/5 scanning lines) into the respective blocksBL1 to BL5, and assigns the divisional regions R of the region B, whoseB-mode element data has been inputted, to the arithmetic cores 18 ofeach of the blocks one by one. Here, the measurement region F is dividedinto 50 regions in the depth direction in such a manner that theresulting 50 consecutive divisional regions R in the depth direction ineach of the regions B include focus points P0 to P49, respectively. Inother words, the focus points are defined so as to correspond to thenumber of arithmetic cores 18 provided in each of the blocks.

The arithmetic cores 18 to which the divisional regions R arerespectively assigned in this manner perform signal processing on theB-mode element data in each of the blocks in the depth direction inparallel and also perform signal processing on the B-mode element datain the plural blocks in the scanning direction in parallel.Specifically, 50 arithmetic cores 18 in each of the blocks performphasing addition on the B-mode element data corresponding to therespective focus points in the assigned divisional region R in the depthdirection in parallel. Similar processing is performed in the pluralblocks in the scanning direction in parallel. The B-mode element datathat has been subjected to phasing addition by the arithmetic cores 18is then subjected to matching addition by the BLC 17 in each of theblocks.

In this manner, since 250 divisional regions R formed by dividing themeasurement region F into 5 regions in the scanning direction and alsointo 50 regions in the depth direction are subjected to phasing additionin parallel, the speed of signal processing can be improved. Morespecifically, provided that the number of scanning lines is “n” and thenumber of focus points is “S”, it is sufficient that n×S/250 focuspoints, where the number of focus points included in the n/5 scanninglines is divided by 50, are sequentially subjected to signal processingfor every frame. Hence, the time required for signal processing ofelement data of one frame can be shortened to 1/250, compared tosequentially subjecting n×S focus points to signal processing for everyframe.

Subsequently, upon verifying designation of CF-mode in Step S13, theoperation proceeds to Step S14 to execute examination in CF-mode.

In an example where B-mode as well as CF-mode are designated, a B-modeultrasonic beam and a CF-mode ultrasonic beam are each transmittedtoward and received from the subject. For transmission and reception ofthe CF-mode ultrasonic beam, as illustrated in FIG. 6, a region ofinterest ROI is defined at a predetermined location in the measurementregion F by the operator, and the transducer array of the probe 1transmits a CF-mode ultrasonic beam toward the region of interest ROIand receives an ultrasonic echo from the region of interest ROI, wherebyCF-mode element data can be obtained. Here, the CF-mode ultrasonic beamis transmitted by the respective elements so as to form, in the regionof interest ROI, scanning lines C1 to Ck, assuming that “k” is thenumber of the scanning lines, and that each scanning line is constitutedwith “m” packets. In the meantime, the B-mode ultrasonic beam istransmitted and received like in Step S12 to thereby obtain B-modeelement data. The obtained CF-mode and B-mode element data aresequentially stored in the element memory 10 frame by frame asillustrated in FIG. 7.

The B-mode element data stored in the element memory 10 is divided into4 regions in the scanning direction to be separately inputted in the BL1to the BL4 of the signal processor 11, and, similarly to Step S12, isdivided into 50 regions in the depth direction. The divisional regions Rthus formed are separately subjected to processing by the arithmeticcores CO0 to C49 in each of the blocks. In this manner, 200 divisionalregions R formed by dividing the measurement region F into 4 regions inthe scanning direction and also into 50 regions in the depth directionare subjected to phasing addition in parallel. Hence, provided that thenumber of scanning lines is “n” and the number of focus points is “S”,the time required for signal processing of element data of one frame canbe shortened to 1/200, compared to sequentially subjecting n×S focuspoints to signal processing for every frame.

On the other hand, CF-mode element data stored in the element memory 10is inputted in the BL 5 through the BLC 17 therein, where CF-modeelement data of every k/50 scanning lines is processed by each of thearithmetic cores 18 constituted with CO0 to C049. More specifically, thearithmetic cores 18 each perform phase matching on every packet which isto constitute each of the k/50 scanning lines as illustrated in FIG. 8,to thereby produce m packet lines CP1 to CPm for each of the scanninglines. Accordingly, the packet lines CP1 to CPm are produced in each ofthe scanning lines Cl to Ck by the plurality of arithmetic cores 18, andthe produced packet lines CP1 to CPm are subjected to autocorrelationprocessing or FFT processing by the SFU 19 in the packet direction,i.e., in the same depth direction. Frequency analysis in the CF-modeprocessing is executed in this manner.

Since B-mode element data and CF-mode element data are assigned to aplurality of blocks and are subjected to signal processing separately inparallel as described above, the processing speed can be improved. Inaddition, FFT processing by the SFU 19 can be performed with theincreased sampling points, while the frame rate is unchanged. Hence,Doppler performance can be improved. Moreover, when improvement in theprocessing speed creates excess time in signal processing in theCF-mode, the number of packets can be increased. Hence, Dopplerperformance can be further improved.

Subsequently, upon verifying designation of PW-mode in Step S15, theoperation proceeds to Step S16 to execute examination in PW-mode.

In an example where B-mode, CF-mode and PW-mode are designated, a B-modeultrasonic beam, a CF-mode ultrasonic beam and a PW-mode ultrasonic beamare transmitted toward and received from the subject to obtain B-modeelement data, CF-mode element data and PW-mode element data. The B-modeultrasonic beam is transmitted and received like in Step S12, while theCF-mode ultrasonic beam is transmitted and received like in Step S14.The B-mode element data, the CF-mode element data and the PW-modeelement data thus obtained are sequentially stored in the element memory10 frame by frame.

The B-mode element data stored in the element memory 10 is divided into3 regions in the scanning direction to be separately inputted in the BL1 to the BL 3 of the signal processor 11. Then, similarly to Step S12,the B-mode element data is divided into 50 regions in the depthdirection to form divisional regions R, which are respectively subjectedto processing by the arithmetic cores CO0 to C49 in each of the blocks.In this manner, 150 divisional regions R formed by dividing themeasurement region F into 3 regions in the scanning direction and alsointo 50 regions in the depth direction are subjected to phasing additionin parallel. Hence, provided that the number of scanning lines is “n”and the number of focus points is “S”, the time required for signalprocessing of element data of one frame can be shortened to 1/150,compared to sequentially subjecting n×S focus points to signalprocessing for every frame.

On the other hand, CF-mode element data stored in the element memory 10is inputted in the BL 4 through the BLC 17 therein and is separatelysubjected to processing by the arithmetic cores 18 constituted with CO0to C049, similarly in Step S14.

Meanwhile, PW-mode element data stored in the element memory 10 isinputted in the BL 5 through the BLC 17 therein, is separately subjectedto processing by the arithmetic cores 18 constituted with CO0 to C049and is also subjected to FFT processing by the SFU 19. At this time, theBL 5 may include a cache memory which is not shown in the drawings, andthe cache memory may maintain the PW-mode element data read out from theelement memory 10, whereby the arithmetic cores 18 can performprocessing on the element data repeatedly.

Since B-mode element data, CF-mode element data and PW-mode element dataare subjected to signal processing separately in the plural blocks inparallel as described above, the processing speed can be improved.

Subsequently, upon verifying designation of M-mode in Step S17, theoperation proceeds to Step S18 to execute examination in M-mode. Thepresent invention enables the following operation, which is not commonlypracticed.

When, for example, the B-mode, the CF-mode, the PW-mode and the M-modeare designated, through transmission and reception of an ultrasonicbeam, element data in the respective modes is sequentially stored in theelement memory 10 frame by frame.

B-mode element data stored in the element memory 10 is divided into 2regions in the scanning direction to be separately inputted in the BL 1and the BL 2 of the signal processor 11, and is divided in the depthdirection to be subjected to processing separately, similarly to StepS12. In this manner, 100 divisional regions R formed by dividing themeasurement region F into 2 regions in the scanning direction and alsointo 50 regions in the depth direction are subjected to phasing additionin parallel. Hence, provided that the number of scanning lines is “n”and the number of focus points is “S”, the time required for signalprocessing of element data of one frame can be shortened to 1/100,compared to sequentially subjecting n×S focus points to signalprocessing in every frame.

In the meantime, CF-mode element data, PW-mode element data and M-modeelement data stored in the element memory 10 are inputted in the BL 3 tothe BL 5, respectively, and are each subjected to processing by the 50arithmetic cores 18 in each of the blocks.

Since B-mode element data, CF-mode element data, PW-mode element dataand M-mode element data are subjected to signal processing separately inthe plural blocks in parallel as described above, the processing speedcan be improved.

Accordingly, element data in the respective examination modes isseparately subjected to signal processing by the signal processor 11,outputted to the DSC 8 through the BUS selector 23 in the BLIF unit 7,and converted to image signals. The image signals thus converted arethen outputted to the monitor 9, whereby an ultrasound diagnostic imageis displayed.

When the B-mode, the CF-mode and the PW-mode are designated in Step S16,for example, a B-mode image, a CF-mode image and a PW-mode image aresimultaneously displayed, as illustrated in FIG. 9. Accordingly, when aplurality of images are simultaneously displayed, the amount ofarithmetic operations increases, and the resulting decrease in the framerate becomes a problem. However, by performing signal processing in therespective modes separately in a plurality of blocks in parallel asdescribed above, the frame rate can be maintained to be constant.

In the examinations in the above-described Steps S12, S14, S16 and S18,element data obtained through transmission and reception of anultrasonic beam is written into and read out from the two buffermemories 21 a and 21 b of the element memory 10 alternately frame byframe.

For instance, in the B-mode examination, as illustrated in FIG. 10, thetransmission circuit 3 transmits transmission pulses to the plurality oftransducers of the probe 1 “n” times in every frame period, therebytransmitting and receiving an ultrasonic beam by the plurality oftransducers. The element data obtained by subjecting the receptionsignals to A/D conversion is written into the buffer memories 21 a and21 b of the element memory 10 alternately frame by frame.

More specifically, during the time period from T1 to T2 in which theultrasonic beam for the frame F1 is transmitted and received, the A/Dconverter 5 is connected to the buffer memory 21 a by the changeoverswitch 22 a as illustrated in FIG. 2, and the element data for the frameF1 is written into the buffer memory 21 a. Subsequently, during the timeperiod from T2 to T3 in which the ultrasonic beam for the frame F2 istransmitted and received, the A/D converter 5 is connected to the buffermemory 21 b by the changeover switch 22 b, and the buffer memory 21 a isconnected by the changeover switch 22 a to the signal processor 11 viathe BUS selector 23. Accordingly, the element data for the frame F2 iswritten into the buffer memory 21 b, while the element data for theframe F1 is read out from the buffer memory 21 a and outputted to thesignal processor 11. Further, during the time period from T3 to T4 inwhich the ultrasonic beam for the frame F3 is transmitted and received,the A/D converter 5 is connected to the buffer memory 21 a by thechangeover switch 22 a, and the buffer memory 21 b is connected by thechangeover switch 22 b to the signal processor 11 via the BUS selector23. Accordingly, the element data for the frame F3 is written into thebuffer memory 21 a, while the element data for the frame F2 is read outfrom the buffer memory 21 b and outputted to the signal processor 11.

As described above, by switching the changeover switches 22 a and 22 bin every frame period, element data is written into and read out fromthe buffer memories 21 a and 21 b alternately frame by frame, enablingthe element data to be written into and read out from the element memory10 in parallel. Hence, loss of time can be suppressed.

When the examinations are carried out in the respective modes asdescribed above, and termination of examination based on the examinationinformation for the present round of examination is verified in StepS19, the operation proceeds to Step S4.

According to this embodiment, since element data is subjected to signalprocessing both in the depth direction and in the scanning direction inparallel in the B-mode examination, the signal processing speed can beimproved. In addition, signal processing is performed in the pluralexamination modes in parallel by assigning the examination modes to therespective blocks, while the signal processing is performed in therespective examination modes separately by the plurality of arithmeticcores 18 in parallel. Hence, the speed of signal processing can beimproved. Moreover, since element data is written into and read out fromthe element memory 10 in parallel, element data is sequentially inputtedinto the signal processor 11, resulting in smooth progress of the signalprocessing.

In the B-mode examination in the above-described Step S12, asillustrated in FIG. 11, the transmission and reception circuits may becontrolled so as to transmit and receive ultrasonic waves as steering aplurality of scanning lines that have been assigned to the respectiveblocks, and while spatial compounding may be also performed in each ofthe blocks. More specifically, an ultrasonic beam being steered istransmitted to and received from the measurement region F to obtain theelement data. Similarly to Step S12, the obtained element data isdivided into 5 regions in the scanning direction to be inputted into theblocks, and is further divided into 50 regions in the depth direction ineach of the blocks to form the divisional regions R, which arerespectively subjected to signal processing by the plurality ofarithmetic cores 18.

Since the element data is subjected to signal processing in the scanningdirection and in the depth direction in parallel as described above, thespatial compounding speed can be improved. Moreover, the number ofscanning lines can be increased when signal processing for spatialcompounding yields excess time due to improvement in the processingspeed, whereby the amount of information resulting from spatialcompounding can be further improved.

In addition, in the above-described embodiment, element data is writteninto and read out from the buffer memories 21 a and 21 b in the elementmemory 10 alternately frame by frame, but more than two buffer memories21 a, 21 b, . . . and 21 i may be included to allow the element data tobe written into and read out from them sequentially frame by frame. Forexample, after transmitting and receiving the ultrasonic beam for theframe F1 and writing the element data for the frame F1 into the buffermemory 21 a, the ultrasonic beam for the frame F2 is transmitted andreceived, and the element data of the frame F2 is written into thebuffer memory 21 b, while the element data of the frame F1 is read outto the signal processor 11 from the buffer memory 21 a. Then, during thetime period for transmission and reception of the ultrasonic beam forthe frame F3, the element data of the frame F3 is written into thebuffer memory 21 c, and the element data of the frame F2 is read out tothe signal processor 11 from the buffer memory 21 b. In this manner, theelement data can be written into and read out from more than two buffermemories 21 a, 21 b, . . . and 21 i sequentially frame by frame, and atthe same time, the element data of one frame read out to the signalprocessor 11 can be assigned to a plurality of arithmetic blockssequentially to be processed by the plurality of arithmetic cores 18.

Embodiment 2

FIG. 12 illustrates a configuration of an ultrasound diagnosticapparatus according to Embodiment 2. The ultrasound diagnostic apparatusperforms so-called photoacoustic imaging (PAI) to image the inside of asubject S using the photoacoustic effect. In the ultrasound diagnosticapparatus in Embodiment 1 as illustrated in FIG. 1, a light irradiationunit 31 is additionally connected to the CPU 13.

The light irradiation unit 31 sequentially emits plural irradiationlight beams (energy beams) L having different wavelengths from oneanother toward the subject S and comprises a semiconductor laser (LD), alight emitting diode (LED), a solid laser, a gas laser or the like. Thelight irradiation unit 31 can use, for example, pulsed laser light beamsas irradiation light beams L and emit pulsed laser light beams towardthe subject S, as sequentially changing the wavelength for each pulse.

For photoacoustic imaging, under the control of the CPU 13, the lightirradiation unit 31 emits irradiation light beams L toward the subjectS. Once a predetermined living tissue V inside the subject S isirradiated with the irradiation light beams L emitted from the lightirradiation unit 31, the living tissue V absorbs light energy of theirradiation light beams L to thereby release photoacoustic waves U(ultrasonic waves) that are elastic waves.

For example, the irradiation light beam L having a wavelength of about750 nm and the irradiation light beam L having a wavelength of about 800nm are emitted from the light irradiation unit 31 sequentially towardthe subject S. In the meantime, oxygenated hemoglobin (hemoglobincombined with oxygen; oxy-Hb) included in plenty in a human artery has ahigher coefficient of molecular absorption for the irradiation lightbeam L with a wavelength of 750 nm than for the irradiation light beam Lwith a wavelength of 800 nm. On the other hand, deoxygenated hemoglobin(hemoglobin not combined with oxygen; deoxy-Hb) included in plenty in ahuman vein has a lower coefficient of molecular absorption for theirradiation light beam L with a wavelength of 750 nm than for theirradiation light beam L with a wavelength of 800 nm. Accordingly, if anartery and a vein are irradiated with the irradiation light beams Lhaving wavelengths of 800 nm and 750 nm respectively, photoacousticwaves U having intensities corresponding to the respective coefficientsof molecular absorption of the artery and the vein will be released.

The photoacoustic waves U released from an artery or a vein, forexample, as described above are received by the transducer arrayarranged in the probe 1 like in Embodiment 1, and the reception signalthereof as the element data of each frame is written into the two buffermemories in the element memory 10. The element data is written into andread out from the two buffer memories sequentially frame by frame, andthe element data read out from the buffer memories is inputted into theblocks of the signal processor 11. In each of the blocks of the signalprocessor 11, the plurality of arithmetic cores 18 are assigned inaccordance with difference in the intensities of reception signals fromthe living tissue V to separately perform signal processing on theelement data to thereby produce image signals, and a photoacoustic image(ultrasound image) in which the living tissue V is imaged is producedbased on the image signals.

The photoacoustic image is preferably displayed together with anultrasound image obtained through transmission and reception ofultrasonic waves by the probe 1. The CPU 13 controls the transmissioncircuit 3 and the light irradiation unit 31 to transmit ultrasonic wavesfrom the probe 1 and emit irradiation light beams L from the lightirradiation unit 31 sequentially, enabling to display an ultrasoundimage and a photoacoustic image simultaneously. In a preferable example,the CPU 13 controls the transmission circuit 3 and the light irradiationunit 31 such that a photoacoustic image of one frame is produced duringgeneration of ultrasound images of 10 frames.

According to this embodiment, since a photoacoustic image can beproduced in addition to an ultrasound image, a multifaceted observationof a subject can be realized, whereby detailed diagnosis can beperformed.

What is claimed is:
 1. An ultrasound image producing method comprisingthe steps of: emitting an energy beam toward a subject; receiving by atransducer array ultrasonic waves generated from the subject upontransmission of the energy beam; generating element data by processingin a reception circuit a reception signal outputted from the transducerarray that has received the ultrasonic waves; writing element data ofone frame from a different frame into each of two or more buffermemories in such a manner that the two or more buffer memoriescorrespond to frames one by one; producing an image signal by assigningthe element data of one frame sequentially read out from the buffermemories to a plurality of arithmetic blocks, and causing each of aplurality of arithmetic cores included in the plurality of arithmeticblocks to perform processing on the element data of one frame assigned;and repeating writing and reading element data into and out from the twoor more buffer memories frame by frame, wherein one examination mode oreach of two or more examination modes for executing an ultrasounddiagnosis selected from among previously set examination modes isassigned to the plurality of arithmetic blocks, and wherein oneexamination mode or two or more examination modes includes B-modeprocessing, a number of divisional regions according to a number of theplurality of arithmetic cores included in the arithmetic block assignedto B-mode processing is defined, by dividing a measurement region in adepth direction and a scanning direction, and the divisional regions areassigned to the arithmetic cores one by one.
 2. The ultrasound imageproducing method according to claim 1, B-mode processing is assigned tothe plurality of arithmetic blocks.
 3. The ultrasound image producingmethod according to claim 1, wherein CF-mode processing and B-modeprocessing are assigned to the plurality of arithmetic blocks.
 4. Theultrasound image producing method according to claim 1, wherein CF-modeprocessing, PW-mode processing and B-mode processing are assigned to theplurality of arithmetic blocks.
 5. The ultrasound image producing methodaccording to claim 1, wherein CF-mode processing, PW-mode processing,B-mode processing and M-mode processing are assigned to the plurality ofarithmetic blocks.
 6. The ultrasound image producing method according toclaim 1, wherein ultrasonic waves as the energy beam are transmitted andreceived in different directions from one another, and the plurality ofarithmetic blocks are assigned to perform spatial compounding.
 7. Theultrasound image producing method according to claim 2, whereinultrasonic waves as the energy beam are transmitted and received indifferent directions from one another, and the plurality of arithmeticblocks are assigned to perform spatial compounding.
 8. The ultrasoundimage producing method according to claim 3, wherein frequency analysisin CF-mode processing is performed in each of the plurality ofarithmetic blocks.